The present invention relates to a shoe for a hoofed animal, such as a horseshoe, and to a method for shoeing a hoofed animal, such as a horse.
The hoof on the foot of a horse comprises a curved covering of horn which protects the front of, and partially encloses, the end of the corresponding digit of the horse. It thus corresponds to a nail on a finger or toe of a human being. The forward end of the hoof is known as the toe, from which the side walls of the hoof extend rearwardly to a heel on either side of the horse's foot. The hoof surrounds a body of tissue which surrounds the digit itself so as to form a capsule, the underside of which forms the sole. Between the hoof and this body of tissue there is an intermediate layer of tissue called the white line. At the rearward end of the horse's foot there is an elastic horny pad of generally triangular shape which is known as the frog.
Domesticated horses are normally shod with horseshoes. A horseshoe is usually attached by nailing to the underside of the hoof to protect it from damage. Conventional horseshoes for horses with healthy feet are made from metal, such as cast iron, steel, or an aluminium alloy. One common design of horseshoe is generally arcuate in shape and sized so as to conform to the size of the hoof to be shod. The size and weight of the horseshoe is normally determined by the type of horse being shod. For example, a working horse will be fitted with heavier shoes than a racehorse. In some designs there may be an upstanding tab at the front of the shoe, or a pair of upstanding tabs positioned one to each side of the front of the shoe, designed to assist in locating the shoe on the hoof and to provide additional protection for the toe of the horse's foot. Other designs of metal horseshoe are known, for example, so-called egg, straight and heart-bar shoes; these are often recommended for use on horses with hoof or lameness problems.
The traditional way of making horseshoes is for the farrier to forge them from bars of iron which are heated on an open hearth forge, hammered to shape on an anvil, and pierced to provide holes for the horseshoe nails. A farrier can produce shoes in advance for fitting to a horse with healthy feet which he has shod previously and whose hoof measurements he already knows. Alternatively he can purchase factory made shoes which can in suitable cases be fitted as received to a horse with healthy feet or which may require to be modified somewhat in shape, or in the position or direction of the holes for the horseshoe nails, using a forge and anvil. Often the horse will be brought to the farrier's smithy to be shoed but many horses are shod at their owner's premises, in which case the farrier will normally bring a portable forge with him in case of need.
Plastics and rubber horseshoes are also known in the art, particularly for shoeing horses suffering from hoof problems. For example, rubber shoes made from a shock-absorbing rubber bonded to a steel or aluminium core are available on the market, as are also horseshoes made from polyurethane and from plastics moulded on to an aluminium core. Some of these mimic the form of the conventional metal shoes and, likewise, are attached to the hoof by nails. Another type of currently available horseshoe is sold in kit form, using polyurethane base plates that have to be cut to the shape of the horse's hoof. Plastics tags are then welded at intervals to the outer rim of the base in an upwardly and radially inward fashion. The shoes are then attached to the hoof by cementing the plastic tags to the outer wall of the hoof. Plastics horseshoes have a number of advantages over metal shoes; for example, they are lighter and can be affixed to a horse's hoof by glueing instead of nailing. Thus they are beneficial for use when a horse is suffering foot problems because they obviate the use of nails. Such foot problems may include laminitis, white line disease (or fungal onychomycosis), navicular disease, sand cracks, or weak heels. Laminitis is a painful condition in which the hoof becomes partly detached from the rest of the hoof capsule along the white line. This can be accompanied by splitting of the hoof. Driving a nail into a hoof in such a condition can exacerbate the problem besides being painful for the horse.
In order to treat an injury to or a disease of a horse's foot, it is usual to cut or abrade away the affected material. Since the pathogens which attack the hoof are generally anaerobic, this helps to speed up a cure. However, there is then the problem of providing support to the trimmed hoof so that the horse can still put weight on its foot without undue discomfort and without exacerbating any misalignment of the horse's leg or, in particular, of the digital bone of the foot, due to the lameness condition from which the horse is suffering. This support can be provided by use of a therapeutic shoe and by using a hoof replacement material to replace the parts that have been cut or abraded away. If the farrier elects to fit a metal shoe then he may have to undertake considerable work to forge a horseshoe of the appropriate shape. If he decides to opt for a plastics or rubber shoe then he may have to cut the shoe to shape or use chemicals with undesirable side effects in order to provide a replacement for the hoof material and any tissue that has been cut or abraded away. If the farrier decides that the horse's foot needs realignment he may decide to provide the horseshoe with a lateral, medial, anterior or posterior extension. This is difficult to effect with a preformed horseshoe.
Foals are sometimes born with deformities such as weak flexor tendons, or club foot syndrome, or may require treatment to correct toe in or toe out conformation. In such instances the farrier will often fit the foal with corrective shoes. One type of foal corrective shoe is formed entirely from a heavy duty plastics material with an upstanding outer cuff which is glued or cemented to the hoof wall. Such shoes can be provided with an appropriate wedge shape and/or with an appropriate lateral, medial, anterior or posterior extension to correct the condition being treated. It has also been proposed to use therapeutic cuffs which can be glued or cemented to the outer wall of the hoof after an appropriate metal shoe has been rivetted to it or to which a shoe can be carefully nailed.
In some cases the farrier may choose to put a pad of leather or of an elastomeric material between the hoof and the horseshoe.
European Patent Specification No. 0 893 057 A1 discloses an open plastic horseshoe with holes for nails and having a bridge piece positioned on one arm for adjustment of the distance between the two arms of the horseshoe.
Use for shoeing a horse of a preformed strip of L-section adhered to a lower wall of its hoof and then adhering a plastics horseshoe thereto is proposed in New Zealand Patent Specification No. 184321.
A horseshoe adhered to a hoof is described in New Zealand Patent Specification No. 221274.
In German Patent Specification No. 19732269 there is taught a horseshoe with an outer hoof cover used as the walking surface which is secured to the hoof by at least two elements. A contact strip binding forms an intermediate layer between the hoof surface and the outer hoof protection. The hoof protection can be made from a thermoplastic material, such as polyester, or vinyl ester, or from an elastomer or a metal.
International Patent Publication No. WO99/15006 describes a helical stock from which circumferential lengths can be cut to be used as horseshoes, the stock comprising a helical coil of plastics material wound about an axis such that the cross section of the coil in a plane containing the axis is constant in shape for any such plane and substantially corresponds to the cross section of a horseshoe in the same plane.
British Patent Specification No. 2334424 teaches a horseshoe having a metal core with a polyurethane coating.
U.S. Pat. Specification No. 5,199,498 proposes a custom horseshoe pad comprising a polymer composition containing at least about 50% by weight of high molecular caprolactone polymers wherein the composition has a melting point of from about 120° F. to about 200° F. (about 48.9° C. to about 93.3° C.). The molecular weight of the caprolactone polymers can range, for example, from about 35,000 to about 60,000. The pad covers areas of the horse's foot that are sensitive and vulnerable to disease and damage. The horseshoe pad is positioned between a horseshoe and the hoof and is intended to expand the overall protection afforded by the standard horseshoe without obviating the need for the shoe.
In U.S. Pat. Specification No. 5,681,350 there is described a rigid and permeable prosthesis that fills the debrided portion of the wall of a horse's hoof having white line disease or the like. This prosthesis includes a mass of particulate material with individual particles coated with a resin so as to cleave to one another at all contact areas and transfer weight, while leaving interconnected pore spaces that allow air and liquid medications to reach the diseased area during the healing process.
International Patent Publication No. WO 94/06285 proposes a lightweight plastic horseshoe which is held to the bottom of a horse's hoof by gluing it thereto and by additionally providing preformed spaced depressions in the underside of the hoof into which extend fasteners attached to the shoe.
In International Patent Publication No. WO 94/12024 a protective covering for a horse's hoof is described which comprises a horseshoe made of polyurethane having convex and concave edges and a polymeric fabric, for example a woven polyurethane fabric, bonded to the horseshoe. The shoe is fitted to the horse's hoof and secured thereto using an acrylic structural adhesive both between the hoof and the shoe and between the polymeric fabric and the outside of the horse's hoof.
A horseshoe with a core of metal which is surrounded by a plastic or rubber material and has apertures for intended for nails is suggested in International Patent Publication No. WO 94/22296.
In International Patent Publication No. WO 95/22252 there is proposed a method of shoeing a horse in which a particulate compound comprising a ground up polymer and an adhesive compound. This particulate compound is poured into a mould into which the horse's hoof, which has previously been cleaned and had an adhesive applied to all voids, is lowered.
International Patent Publication No. WO 96/01044 is concerned with a horseshoe having holes for horseshoe nails and including a resilient material.
Another proposal is to be found in International Patent Publication No. WO 98/24312. This comprises a core of metal with holes for horseshoe nails which is substantially entirely enclosed in a substantially deformable material such as a rubber or rubber-like material.
A hoof protector for hooves of horses is suggested in International Patent Publication No. WO 99/40782 which has a horseshoe shaped base body of plastic and at least one fixed front setting element.
International Patent Publication No. WO 99/65298 describes a shock-absorbing horseshoe which is secured to a horse's hoof with nails whose nail heads abut against an intermediate resilient layer.
European Patent Specification No. 0 651 943 A1 teaches a boot for horses' hooves made of flexible material.
A plastic covering for a horse's hoof with a two part laminate construction for attachment to the hoof of a horse using nails is disclosed in European Patent Specification No. 0 823 209 A2. The upper layer comprises a stable plastic material, such as a thermally formable plastic (e.g. polyurethane, polyamide or an elastomer), while the lower layer is less hard and is also formed from a plastic.
European Patent Specification No. 0 832 560 A1 teaches a horseshoe which is at least partially enclosed in a resilient material which has holes for conventional nails.
European Patent Specification No. 0 860 115 A1 discloses a horseshoe with a shock-absorbing sole plate with a peripheral indentation for receipt of a steel band to which are fixed six supports through which nails can be driven into the horse's hoof.
As pointed out above most, if not all, plastics horseshoes currently on the market suffer from the disadvantage that they are time-consuming and cumbersome to apply, particularly those that have to be assembled from a kit of parts. This is at least in part due to the necessity to make the horseshoe fit a damaged foot from which a considerable amount of hoof may have been cut away. Since the horse is lame it will usually be inconvenient or impractical for it to be brought to the smithy so that the farrier has to take his equipment to the horse's own stable. This tends to make it more inconvenient for the farrier to have to reshape a horseshoe away from his own smithy.
There is accordingly a need in the art for an improved form of horseshoe which can be used in therapy for treatment of such diseases as laminitis and which is simple to apply to the foot of a horse being treated. There is a further need for a novel design of horseshoe which can be readily adapted to fit and provide support for a foot of a hoofed animal from which a variable amount of hoof material, and possibly also other tissue, may have been cut or abraded away. There is still further a need for a horseshoe which can be readily formed to an appropriate shape for treatment of a horse that is suffering from foot problems, particularly when such shaping has to be accomplished in the horse's own stable or stableyard rather than at a farrier's smithy. Additionally there is a need for a horseshoe which can be fitted to the hoof of a horse suffering from laminitis or other condition causing lameness without the use of nails and in a manner which substantially avoids trauma for the horse. Yet again there is a need for an improved method of shoeing a horse that obviates the need to drive nails into the hoof of the horse. There is also a need for a method of shoeing a horse suffering from a debilitating condition, such as laminitis, which avoids trauma for the horse. Moreover there is a need to provide a novel method of shoeing a horse which avoids the use of a forge. Another need is for a method of shoeing a horse which utilises horseshoes which can be moulded to a hoof and attached thereto in a simple manner without use of a forge.